Fiber optic cables and assemblies and the performance thereof

ABSTRACT

A fiber optic jumper assembly comprising at least one bend performance optical fiber comprising a core region and a cladding region surrounding the core region, the cladding region comprising an annular hole-containing region comprised of non-periodically disposed holes, a protective covering positioned over the at least one bend performance optical fiber, and at least one connector mounted upon each end of the at least one bend performance optical fiber. A preconnectorized fiber optic jumper assembly comprising a microstrucutred fiber having a delta attenuation of 0.00 dB at 5 wraps about a 6 mm diameter at a reference wavelength of 1625 nm.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. Ser. No. 11/638,610 filed Dec.13, 2006, the entire content of which is hereby incorporated byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to fiber optic cables and jumperassemblies and the performance thereof. By way of example, the inventionis related to assemblies such as optical fiber jumpers having at leastone bend performance optical fiber, thereby enabling previouslyunattainable optical performance characteristics.

BACKGROUND OF THE INVENTION

Along with the increase in the deployment of “Fiber-to-the-Premises”(FTTP) optical networks, a need has arisen for increasing theperformance, manageability, handleability and flexibility of fiber opticcables, cable assemblies and network components in general. With respectto outdoor installation environments, cables, cable assemblies and othernetwork components are being developed that are more easilyinterconnected and installed within their environment, such as withinaerial installation environments or through small diameter conduit. Withrespect to indoor environments and multi-dwelling units, cables, cableassemblies, connection terminals and other network components are beingdeveloped to improve installation aesthetics and handle theinterconnection of an increasing number of subscribers. Within bothenvironments, it would be desirable to develop components that performbetter, are more flexible to installation stresses and are more robustand long lasting, thus saving time and costs.

Conventional cables, cable assemblies, fiber optic hardware and othernetwork components typically define structure that accommodates, and isin part, limited by the physical characteristics of the optical fiberscontained therein. In other words, it is oftentimes the case that thephysical and performance limitations of the optical fibers partly defineassembly structure and processes associated with manufacturing saidassemblies. Thus, optical fibers are one limiting factor in theevolution of fiber optic networks.

Accordingly, what is desired are fiber optic cables and jumperassemblies that include bend performance optical fiber having improvedbending performance characteristics over conventional cables andassemblies. It would be desirable to provide cables and jumperassemblies capable of being significantly bent or wrapped, eitherstand-alone or around network structure, without suffering appreciableloss. Such cables and assemblies including bend performance fiber wouldbe more accepting of handling without damage.

BRIEF SUMMARY OF THE INVENTION

To achieve the foregoing and other objects, and in accordance with thepurposes of the invention as embodied and broadly described herein, thepresent invention provides various embodiments of fiber optic cables,jumpers and other assemblies including bend performance optical fiber inat least a portion thereof. The present invention further provides bendperformance optical fiber suitable for use in fiber optic cables, fiberoptic hardware and other assemblies, wherein the bend performanceoptical fiber comprises certain physical and performance characteristicsthat lends itself to reduced component size, tighter bend radiustolerances without degraded performance, and relaxes fiber routing andhandling requirements.

In one embodiment, the bend performance optical fiber of the presentinvention is a microstructured optical fiber comprising a core regionand a cladding region surrounding the core region, the cladding regioncomprising an annular hole-containing region comprised ofnon-periodically disposed holes or voids, such that the optical fiber iscapable of single mode transmission at one or more wavelengths in one ormore operating wavelength ranges. The non-periodically disposed holesare randomly or non-periodically distributed across a portion of thefiber. The holes may be stretched (elongated) along the length (i.e. ina direction generally parallel to the longitudinal axis) of the opticalfiber, but may not extend the entire length of the entire fiber fortypical lengths of transmission fiber.

In other embodiments, the bend performance fiber of the presentinvention may comprise at least a portion of fiber optic cables, fiberoptic cable assemblies, network connection terminals, fiber optichardware or any other fiber optic network component including at leastone optical fiber maintained therein, routed therein or routedtherethrough.

Additional features and advantages of the invention will be set forth inthe detailed description which follows, and in part will be readilyapparent to those skilled in the art from that description or recognizedby practicing the invention as described herein, including the detaileddescription which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description present exemplary embodiments of theinvention, and are intended to provide an overview or framework forunderstanding the nature and character of the invention as it isclaimed. The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated into and constitutea part of this specification. The drawings illustrate variousembodiments of the invention, and together with the detaileddescription, serve to explain the principles and operations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages of the presentinvention are better understood when the following detailed descriptionof the invention is read with reference to the accompanying drawings, inwhich:

FIG. 1 is a schematic diagram illustrating a cross-section of a bendperformance optical fiber operable in accordance with an exemplaryembodiment of the present invention;

FIG. 2 is a cross-sectional image of a microstructured bend performanceoptical fiber illustrating an annular hole-containing region comprisedof non-periodically disposed holes;

FIG. 2 a is a cross-sectional image of a fiber optic cable using themicrostructured bend performance optical fiber of FIG. 1 according tothe present invention;

FIG. 2 b is a cross-sectional image of another fiber optic cable usingthe microstructured bend performance optical fiber of FIG. 1 accordingto the present invention;

FIG. 2 c is a plan view of the fiber optic cable of FIG. 2 a being bentin an aggressive manner to demonstrate a minimum bend radius;

FIG. 3 illustrates one embodiment of an optical fiber jumper assemblyusing microstructured bend performance optical fiber of FIG. 1completing about one turn about a small diameter structure;

FIG. 4 illustrates the optical fiber jumper assembly of FIG. 3completing multiple turns about a structure;

FIG. 5 illustrates the optical fiber jumper assembly of FIG. 3 showntied in a knot;

FIG. 6 illustrates a portion of an optical fiber jumper assemblyincluding bend performance fiber bent about 90 degrees around genericnetwork structure; and

FIG. 7 illustrates a portion of an optical fiber jumper assemblyincluding bend performance fiber bent about 180 degrees around genericnetwork structure.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully hereinafter withreference to the accompanying drawings in which exemplary embodiments ofthe invention are shown. However, the invention may be embodied in manydifferent forms and should not be construed as limited to theembodiments set forth herein. These exemplary embodiments are providedso that this disclosure will be both thorough and complete, and willfully convey the scope of the invention and enable one of ordinary skillin the art to make, use and practice the invention. Like referencenumbers refer to like elements throughout the various drawings.

FIG. 1 depicts a representation of a bend performance optical fiber 1suitable for use in fiber optic cables, cables assemblies, fiber optichardware and other network components of the present invention. Thepresent invention is advantageous because it permits assemblies havingaggressive bending/installation solutions while optical attenuationremains extremely low. As shown, bend performance optical fiber 1 is amicrostructured optical fiber having a core region and a cladding regionsurrounding the core region, the cladding region comprising an annularhole-containing region comprised of non-periodically disposed holes suchthat the optical fiber is capable of single mode transmission at one ormore wavelengths in one or more operating wavelength ranges. The coreregion and cladding region provide improved bend resistance, and singlemode operation at wavelengths preferably greater than or equal to 1500nm, in some embodiments also greater than about 1310 nm, in otherembodiments also greater than 1260 nm. The optical fibers provide a modefield at a wavelength of 1310 nm preferably greater than 8.0 microns,more preferably between about 8.0 and 10.0 microns. In preferredembodiments, optical fiber disclosed herein is thus single-modetransmission optical fiber.

In some embodiments, the microstructured optical fibers disclosed hereincomprises a core region disposed about a longitudinal centerline, and acladding region surrounding the core region, the cladding regioncomprising an annular hole-containing region comprised ofnon-periodically disposed holes, wherein the annular hole-containingregion has a maximum radial width of less than 12 microns, the annularhole-containing region has a regional void area percent of less thanabout 30 percent, and the non-periodically disposed holes have a meandiameter of less than 1550 nm.

By “non-periodically disposed” or “non-periodic distribution”, we meanthat when one takes a cross-section (such as a cross-sectionperpendicular to the longitudinal axis) of the optical fiber, thenon-periodically disposed holes are randomly or non-periodicallydistributed across a portion of the fiber. Similar cross sections takenat different points along the length of the fiber will reveal differentcross-sectional hole patterns, i.e., various cross-sections will havedifferent hole patterns, wherein the distributions of holes and sizes ofholes do not match. That is, the holes are non-periodic, i.e., they arenot periodically disposed within the fiber structure. These holes arestretched (elongated) along the length (i.e. in a direction generallyparallel to the longitudinal axis) of the optical fiber, but do notextend the entire length of the entire fiber for typical lengths oftransmission fiber.

For a variety of applications, it is desirable for the holes to beformed such that greater than about 95% of and preferably all of theholes exhibit a mean hole size in the cladding for the optical fiberwhich is less than 1550 nm, more preferably less than 775 nm, mostpreferably less than 390 nm. Likewise, it is preferable that the maximumdiameter of the holes in the fiber be less than 7000 nm, more preferablyless than 2000 nm, and even more preferably less than 1550 nm, and mostpreferably less than 775 nm. In some embodiments, the fibers disclosedherein have fewer than 5000 holes, in some embodiments also fewer than1000 holes, and in other embodiments the total number of holes is fewerthan 500 holes in a given optical fiber perpendicular cross-section. Ofcourse, the most preferred fibers will exhibit combinations of thesecharacteristics. Thus, for example, one particularly preferredembodiment of optical fiber would exhibit fewer than 200 holes in theoptical fiber, the holes having a maximum diameter less than 1550 nm anda mean diameter less than 775 nm, although useful and bend resistantoptical fibers can be achieved using larger and greater numbers ofholes. The hole number, mean diameter, max diameter, and total void areapercent of holes can all be calculated with the help of a scanningelectron microscope at a magnification of about 800× and image analysissoftware, such as ImagePro, which is available from Media Cybernetics,Inc. of Silver Spring, Md., USA.

The optical fibers disclosed herein may or may not include germania orfluorine to also adjust the refractive index of the core and or claddingof the optical fiber, but these dopants can also be avoided in theintermediate annular region and instead, the holes (in combination withany gas or gases that may be disposed within the holes) can be used toadjust the manner in which light is guided down the core of the fiber.The hole-containing region may consist of undoped (pure) silica, therebycompletely avoiding the use of any dopants in the hole-containingregion, to achieve a decreased refractive index, or the hole-containingregion may comprise doped silica, e.g. fluorine-doped silica having aplurality of holes.

In one set of embodiments, the core region includes doped silica toprovide a positive refractive index relative to pure silica, e.g.germania doped silica. The core region is preferably hole-free. Asillustrated in FIG. 1, in some embodiments, the core region 170comprises a single core segment having a positive maximum refractiveindex relative to pure silica Δ₁ in %, and the single core segmentextends from the centerline to a radius R₁. In one set of embodiments,0.30%<Δ₁<0.40%, and 3.0 μm μm<R₁<5.0 μm. In some embodiments, the singlecore segment has a refractive index profile with an alpha shape, wherealpha is 6 or more, and in some embodiments alpha is 8 or more. In someembodiments, the inner annular hole-free region 182 extends from thecore region to a radius R₂, wherein the inner annular hole-free regionhas a radial width W12, equal to R2−R1, and W12 is greater than 1 μM.Radius R2 is preferably greater than 5 μm, more preferably greater than6 μm. The intermediate annular hole-containing region 184 extendsradially outward from R2 to radius R3 and has a radial width W23, equalto R3−R2. The outer annular region 186 extends radially outward from R3to radius R4. Radius R4 is the outermost radius of the silica portion ofthe optical fiber. One or more coatings may be applied to the externalsurface of the silica portion of the optical fiber, starting at R4, theoutermost diameter or outermost periphery of the glass part of thefiber. The core region 170 and the cladding region 180 are preferablycomprised of silica. The core region 170 is preferably silica doped withone or more dopants. Preferably, the core region 170 is hole-free. Thehole-containing region 184 has an inner radius R2 which is not more than20 μm. In some embodiments, R2 is not less than 10 μM and not greaterthan 20 μm. In other embodiments, R2 is not less than 10 μm and notgreater than 18 μm. In other embodiments, R2 is not less than 10 μm andnot greater than 14 μm. Again, while not being limited to any particularwidth, the hole-containing region 184 has a radial width W23 which isnot less than 0.5 μm. In some embodiments, W23 is not less than 0.5 μmand not greater than 20 μm. In other embodiments, W23 is not less than 2μm and not greater than 12 μm. In other embodiments, W23 is not lessthan 2 μm and not greater than 10 μm.

Such fiber can be made to exhibit a fiber cutoff of less than 1400 nm,more preferably less than 1310 nm, a 20 mm macrobend induced loss at1550 nm of less than 1 dB/turn, preferably less than 0.5 dB/turn, evenmore preferably less than 0.1 dB/turn, still more preferably less than0.05 dB/turn, yet more preferably less than 0.03 dB/turn, and even stillmore preferably less than 0.02 dB/turn, a 12 mm macrobend induced lossat 1550 nm of less than 5 dB/turn, preferably less than 1 dB/turn, morepreferably less than 0.5 dB/turn, even more preferably less than 0.2dB/turn, still more preferably less than 0.01 dB/turn, still even morepreferably less than 0.05 dB/turn, and a 8 mm macrobend induced loss at1550 nm of less than 5 dB/turn, preferably less than 1 dB/turn, morepreferably less than 0.5 dB/turn, and even more preferably less than 0.2dB-turn, and still even more preferably less than 0.1 dB/turn.

An example of a suitable fiber is illustrated in FIG. 2. The fiber inFIG. 2 comprises a core region that is surrounded by a cladding regionthat comprises randomly disposed voids which are contained within anannular region spaced from the core and positioned to be effective toguide light along the core region. Other optical fibers andmicrostructured fibers may be used in the present invention. Additionaldescription of microstructured fibers used in the present invention aredisclosed in pending U.S. patent application Ser. No. 11/583,098 filedOct. 18, 2006; and, Provisional U.S. patent application Ser. Nos.60/817,863 filed Jun. 30, 2006; 60/817,721 filed Jun. 30, 2006;60/841,458 filed Aug. 31, 2006; and 60/841,490 filed Aug. 31, 2006; allof which are assigned to Corning Incorporated; and incorporated hereinby reference.

Optical fiber cables of the present invention allow aggressive bendingsuch as for installation, slack storage, and the like while inhibiting abend radii that allows damage and/or breaks the optical fiber. FIG. 2 ashows a cross-sectional view of explanatory fiber optic cable 100 havingoptical fiber 1 within a protective covering 8. Generally speaking,optical fiber 1 is maintained within at least one protective coveringsuch as a buffer layer and/or a jacket and is referred to herein as a“fiber optic cable”. As shown, protective covering 8 includes a bufferlayer 8 a disposed about optical fiber 1 and a jacket 8 b. Additionally,fiber optic cable 100 also includes a plurality of optional strengthmembers 14 disposed between buffer layer 8 a and jacket 8 b. Strengthmembers 14 can also include a water-swellable component for blocking themigration of water along the fiber optic cable. FIG. 2 b depicts analternate fiber optic cable 100′ that is similar to fiber optic cable100, but it does not include strength members and consequently has asmaller outer diameter such as about 4 millimeters if the jacket wallthickness remains the same. Additionally, since the strength members areomitted it is possible to remove the buffer layer and jacket from thefiber optic cable in a single step. Other fiber optic cables and/orother assembly designs are also possible according to the concepts ofthe invention. By way of example, variations of fiber optic cables 100and 100′ can be preconnectorized with a connector for plug and playconnectivity. For instance, fiber optic cables can include a hardenedplug and connector such as an Opti-Tap or Opti-Tip available fromCorning Cable Systems of Hickory, N.C.

Protective covering 8 uses a bend radius control mechanism forprotecting the optical fiber by inhibiting damage and/or breaking of theoptical fiber as the fiber optic cable is bent into small bend radiiwhile still providing a highly flexible fiber optic cable design. Inother words, the bend radius control mechanism maintains a minimum bendradii for the optical fiber so damage and/or breaking is avoided. By wayof example, fiber optic cable 100 can be tied in a knot, bent aboutsmall structures, and the like while having extremely low opticalattenuation; however, the fiber optic cable still should prevent damageand/or breaking of the optical fiber during these installations.Previously, conventional fiber optic cables would have high opticalattenuation or go dark before breaking the optical fiber was a concern,thus the craft avoided using small bend radii for preserving opticalperformance. One benefit of the present invention is that the fiberoptic cable designs are suitable for rugged installations both by thecraft and untrained individuals.

Robustness of the fiber optic cable design is accomplished by suitablecoupling with the protective covering for inhibiting buckling of theoptical fiber within the same. Additionally, maintaining couplingbetween jacket 8 b and strength members 14 inhibits the transfer oftensile forces to optical fiber 1. Coupling is accomplished using apressure extrusion process and can allow aggressive bending of the fiberoptic cable while maintaining a suitable coupling level. Consequently,the coupling results in very little to no construction stretch for thestrength members. As used herein, construction stretch means that all ofthe cable components are not simultaneously stretched when applying atensile force to the fiber optic cable. Illustratively, a fiber opticcable exhibiting construction stretch typically has the jacket andoptical fiber supporting the initially applied tensile force, but thestrength members do not. Thus, as the jacket and optical fiber arestretched to a point where the slack in the strength members is removedand the strength members also begin to support the load. Thisconstruction stretch is problematic since it initially allows theoptical fiber to strain, which limits the ultimate tensile strength ofthe fiber optic cable. Additionally, after the tensile force is removedfrom the fiber optic cable the jacket stretched before the opticalfiber, thereby allowing buckling and/or compression of the optical fiberwithin the fiber optic cable that can cause optical losses. Any suitabletype of material may be used for protective covering 8 such aspolyurethanes (PU), polyvinylchloride (PVC), polyethylenes (PE),polyproplyenes (PP), UV curable materials, etc. depending on the desiredconstruction and characteristics. Additionally, protective coverings 8can use flame-retardant materials such as a flame-retardant PVC or thelike as known in the art. Desirably, fiber optic cables of the inventionuses highly-flexible and robust designs that allow aggressive bending ofthe cable while maintaining a minimum bend radii.

More specifically, fiber optic cable 100 is designed so that it ishighly flexible, maintains a minimum bend radius to inhibit breaking ofthe optical fiber when aggressively bent, and have enough couplingbetween protective covering 8 and optical fiber 1 to inhibit buckling ofthe optical fiber within protective covering 8. By way of example, fiberoptic cable 100 includes optical fiber 1 having a plenum-grade bufferlayer 8 a with an outer diameter of about 900 microns. Other types ofmaterials, sizes, shapes, etc are also possible for the buffer layer.Thereafter, four strength members 14 were run in a parallelconfiguration (i.e., no stranding) about the buffered optical fiberbefore jacket 8 b was applied. Eliminating stranding of strength members14 is also advantageous since it allows for increased line speeds.Jacket 8 b was pressure extruded using a PU material available fromHuntsman available under the tradename Irogran A78 P 4766. The jacketmaterial used had a relatively high ultimate elongation (i.e.,elongation before breaking) measured according to DIN 53504 (a Germanmeasurement standard), thereby providing a highly flexible fiber opticcable design. Jackets for fiber optic cables of the invention have anultimate elongation that is about 500% or greater such as about 600% orgreater, and even about 700% or greater. The PU jacket material used hadan ultimate elongation of about 800% along with a 300% tensile modulusof about 8.0 MPa. Additionally, jacket 8 b had an outer diameter ofabout 5 millimeters with an inner diameter of about 1.7 millimeters.Consequently, fiber optic cable 100 had an excellent flexibility whilestill inhibiting breaking of the optical fiber when aggressively bentfor instance when fiber optic cable is bent like a hairpin as shown inFIG. 2 c the bend radius control mechanism is provided by jacket 8 balong with its coupling characteristics. In other words, the bend radiuscontrol mechanism of jacket 8 b provides a minimum bend diameter ofabout 5 millimeters (e.g., about two times the radius of the fiber opticcable) for inhibiting breaking of the optical fiber when bent as shownin FIG. 2 c. Using the bend radius control mechanism also improves crushperformance of the fiber optic cable since the jacket is relativelythick and highly flexible. Furthermore, the optical performance of fiberoptic cable 100 during aggressive bendng is impressive compared withconventional fiber optic cables.

To test the optical performance of fiber optic cable 100, a corner bendtest was conducted as described below. The corner bend test routed aportion of fiber optic cable 100 over a 90 degree edge (i.e., nearly azero bend radius) and weights were hung from the fiber optic cable toapply a constant force at the bend while measuring a delta attenuation(e.g., change in attenuation) at a reference wavelength of 1625nanometers due to the applied force. The corner bend test used fiberoptic cable 100 and a similar fiber optic cable design using a SMF28-eoptical fiber available from Corning, Inc. The results for the cornerbend test are summarized in Table 1 below.

TABLE 1 Corner Bend Test Fiber Optic Conventional Cable 100 Cable DeltaDelta Attenuation (dB) Attenuation (dB) 1310 1550 1625 1310 1550 1625Load (kg) nm nm nm nm nm nm 0 0.00 0.00 0.00 0.00 0.01 0.02 0.6 1.163.16 5.21 0.01 0.02 0.04 1 2.51 8.14 11.06  0.01 0.06 0.09 5 — — — 0.030.18 0.22 10 — — — 0.03 0.15 0.22

As depicted in Table 1, the conventional cable had elevated levels ofdelta attenuation at all wavelengths with a load of 0.6 kilograms.Moreover, the delta attenuation was so high above a load of 1 kilogramthat measurements were not taken. On the other hand, fiber optic cable100 had low delta attenuation values with loads up to 10 kilograms. Byway of example, fiber optic cable 100 had a delta attenuation of about0.1 dB or less for the corner bend test with a load of 1 kilogram at areference wavelength of 1625 nanometers. Other testing was alsoperformed such as bending fiber optic cable 100 about a mandrel with agiven diameter along with a conventional fiber optic cable forcomparison purposes. More specifically, a delta attenuation (dB) for theloss was measured after wrapping a predetermined number of turns (i.e.,each turn is about 360 degrees) of fiber optic cable around a mandrelwith a given diameter.

TABLE 2 Mandrel Wrap Test at a Reference Wavelength of 1625 nanometersConventional Cable Fiber Optic Cable 100 Delta Attenuation (dB) DeltaAttenuation (dB) Number of 4.6 mm 7.5 mm 15 mm 4.6 mm 7.5 mm 15 mm Turnsmandrel mandrel mandrel mandrel mandrel mandrel 0 — — 0.00 0.00 0.000.00 1 — — 3.10 0.39 0.10 0.07 2 — — 7.96 0.56 0.18 0.11 3 — — 11.580.83 0.33 0.17 4 — — 16.03 1.18 0.53 0.23 5 — — 20.19 1.43 0.68 0.23

As depicted in Table 2, the conventional cable had elevated levels ofdelta attenuation when it was wrapped about a 15 millimeter mandrel.Moreover, the delta attenuation was so large with mandrels smaller than15 millimeters that the measurements were not taken. On the other hand,fiber optic cable 100 had delta attenuation values that were more thanan order of magnitude lower using a 15 millimeter mandrel. By way ofexample, fiber optic cable 100 had a delta attenuation of about 0.33 dBor less when wrapped 3 turns about a 7.5 millimeter mandrel at areference wavelength of 1625 nanometers.

Another example of assemblies useful with the concepts of the presentinvention are optical fiber jumper assemblies that are, generallyspeaking, used within structures for interconnection purposes. FIGS. 3-5depict an explanatory optical fiber jumper assembly 15 (hereinafter“jumper assembly”) using optical fiber 1 and is shown in variousconfigurations to illustrate physical and performance capabilities ofassemblies according to the concepts of the invention. Moreover, jumperassemblies represented by jumper assembly 15 were tested for opticalperformance and compared with conventional jumper assemblies aspresented below. Jumper assemblies of the invention preserve opticalattenuation during, for example, macrobending down to levels notpreviously attainable with previous constructions.

As shown, jumper assembly 15 is connectorized at each end using SCconnectors 12, such as those available from Coining Cable Systems ofHickory, N.C., using techniques known in the art. Of course, jumperassemblies may include any length of fiber optic cable, type ofconnector and/or number of optical fibers capable of performinginterconnections within an optical network. It is envisioned that ajumper assembly may be connectorized at each end using similar ordissimilar connector types such as LC, FC, MT, MTP, among others. Thejumper assembly 15 may be aggressively bent, either stand-alone or aboutnetwork structure, such as for installation, slack storage and routingwithout suffering appreciable attenuation and without damage and/orbreaks to the optical fiber. The at least one optical fiber 1 is withina protective covering 10 such as, but not limited to, a coating, abuffer, or a jacket. In one example, the fiber 1 may be upjacketed toabout 500 um or about 900 um. The jumper assembly may further includestrength members, such as aramid strength members, as is commonly knownin the art. Other fiber optic jumper assemblies are also possibleaccording to the concepts of the invention.

The protective covering 10 may be made from material including bendradius control properties for protecting the at least one optical fiberwithin by inhibiting damage and/or breaking of the optical fiber as thejumper assembly is bent into small bend radii while still providing ahighly flexible juniper design. By way of example, the jumper assembly15 can be tied in a knot, bent about small structures, and the likewhile having extremely low optical attenuation.

Referring specifically to FIG. 3, jumper assembly 15 is shown completingone turn or wrap about a mandrel 14. Mandrel 14 is shown to provide aguide for bending jumper assembly 15 about a structure, and genericallymandrel 14 represents a portion of network structure about which thejumper assembly is installed (e.g., a network interface device (NID), acabinet, routing guide, connector housing, connector port or the like).Mandrel 14 defines a diameter, for example, the diameter is about 10millimeters or about 6 millimeters, but other sizes are possible.Referring specifically to FIG. 4, jumper assembly 15 is shown wrappedabout the mandrel 14 and completing about five turns. Referringspecifically to FIG. 5, jumper assembly 15 is shown tied in a knot.

Table 3 details optical performance data for different fiber optic cabledesigns at a reference wavelength of 1625 nanometers. More specifically,a delta attenuation (dB) for the loss was measured after wrapping apredetermined number of turns (i.e., each turn is about 360 degrees) offiber optic cable around a mandrel with a given diameter. Table 3depicts the results for two different single fiber cable (SFC) designs(i.e., a 2.0 millimeter SFC and a 2.9 millimeter SFC) that were used asa portion of the tested jumper assemblies. Each of the SFC designs useda conventional optical fiber and a microstructured bend performanceoptical fiber, thereby resulting in four jumper assemblies for testing.Additionally, two different microstructured bend performance opticalfibers were used in the jumper assemblies of the present invention tocompare performance, listed in the table below as Type I and Type IIbend performance fibers. The conventional optical fiber used in theconventional jumper assemblies was a SMF-28e optical fiber availablefrom Corning Incorporated of Corning, N.Y. Both the 2.0 millimeter andthe 2.9 SFC designs included an optical fiber having a 900 micron bufferlayer thereon that was surrounded by a plurality of aramid strengthmembers and a jacket. The differences between the 2.0 millimeter and 2.9millimeter SFC include the jacket wall thickness (e.g., respectivelyabout 0.33 millimeters and about 0.45 millimeters) and the quantity ofaramid used.

TABLE 3 Delta Attenuation (dB) at 1625 nanometers after Wrapping Arounda Mandrel Delta At- Delta Delta Delta tenuation Mandrel AttenuationAttenuation Attenuation 2.9 mm Diameter - # Conventional Conventional2.0 mm SFC SFC of Turns 2.0 mm SFC 2.9 mm SFC Type I Type II 10 mm - 1Turns 25.42 dB 27.20 dB 0.11 dB 0.00 dB 10 mm - 2 Turns 41.30 dB 42.30dB 0.27 dB 0.00 dB 10 mm - 3 Turns 45.00 dB 45.00 dB 0.42 dB 0.00 dB 10mm - 4 Turns 45.89 dB 45.80 dB 0.70 dB 0.00 dB 10 mm - 5 Turns 46.20 dB46.20 dB 0.93 dB 0.00 dB  6 mm - 1 Turns 46.20 dB 46.00 dB 0.46 dB 0.00dB  6 mm - 2 Turns 46.20 dB 46.00 dB 0.98 dB 0.00 dB  6 mm - 3 Turns46.20 dB 46.00 dB 1.70 dB 0.00 dB  6 mm - 4 Turns 46.20 dB 46.00 dB 2.72dB 0.00 dB  6 mm - 5 Turns 46.20 dB 46.00 dB 3.12 dB 0.00 dB 90 degreebend  0.86 dB  0.53 dB 0.03 dB 0.00 dB

As depicted in Table 3, the conventional SFC jumpers had elevated levelsof delta attenuation at all turns about both mandrel diameters. Incomparison, the jumper assemblies including both Type I and II fiber haddelta attenuation orders of magnitude lower, and with respect to thejumper assembly including Type II bend performance fiber, there was nodelta attenuation at all turns about each mandrel diameter. Further,both the conventional and Type I and II jumper assemblies were bentabout a 90 degree bend, such as a corner bend test, and the jumperassemblies including bend performance fiber outperformed theconventional jumpers. By way of example, the jumper assembly 15including bend performance fiber had a delta attenuation of about 0.03dB or less for the 90 degree bend test at a reference wavelength of 1625nanometers.

Bend performance fibers of the present invention may be included withinvarious cable types and cable assemblies to achieve highly flexiblecables to facilitate installation and require less skill in handling.The cables and cable assemblies described herein may be installed withinfiber optic hardware such as local convergence points for multi-dwellingunits, cross-connect frames and modules, and surface, pad and polemounted local convergence points showing smaller size and higherdensity. Referring to FIGS. 6-7, a portion of the jumper assembly withthe protective covering 10 is shown wrapped around generic networkstructure 20. An angle theta 22 corresponds to a portion of a turn aboutthe generic structure 20. Generic structure 20 may include, but is notlimited to, structure of fiber optic cable assemblies, hardware, spools,thru holes, connector ports, routing guides, cabinets or any otherstructure within the network.

The foregoing is a description of various embodiments of the inventionthat are given here by way of example only. Although fiber optic cablesand jumper assemblies including bend performance fiber in at least aportion thereof have been described with reference to preferredembodiments and examples thereof, other embodiments and examples mayperform similar functions and/or achieve similar results. All suchequivalent embodiments and examples are within the spirit and scope ofthe present invention and are intended to be covered by the appendedclaims.

1. A fiber optic jumper assembly, comprising: at least one bendperformance optical fiber comprising a core region, a hole-free innerannular cladding region surrounding the core region, an annularhole-containing cladding region surrounding the inner annular claddingregion and comprised of non-periodically disposed holes, and an outerhole-free cladding region surrounding the annular hole-containingcladding region; a protective covering positioned over the at least onebend performance optical fiber; and at least one connector mounted uponat least one end of the at least one bend performance optical fiber. 2.The jumper assembly of claim 1, wherein the jumper assembly has a deltaattenuation of 0.11 dB or less at one turn about a 10 mm diameterstructure at a reference wavelength of 1625 nanometers.
 3. The jumperassembly of claim 1, wherein the jumper assembly has a delta attenuationof 0.93 dB or less at five turns about a 10 mm diameter structure at areference wavelength of 1625 nanometers.
 4. The jumper assembly of claim1, wherein the jumper assembly has a delta attenuation of 0.46 dB orless at one turn about a 6 mm diameter structure at a referencewavelength of 1625 nanometers.
 5. The jumper assembly of claim 1,wherein the jumper assembly has a delta attenuation of 3.12 dB or lessat five turns about a 6 mm diameter at a reference wavelength of 1625nanometers.
 6. The jumper assembly of claim 1, wherein the at least onebend performance optical fiber has a 12 mm macrobend induced loss at1550 nm of less than 0.1 dB/turn.
 7. The jumper assembly of claim 1,wherein the at least one bend performance optical fiber has a 12 mmmacrobend induced loss at 1550 nm of less than 0.05 dB/turn.
 8. Thejumper assembly of claim 1, wherein the at least one bend performanceoptical fiber has an 8 mm macrobend induced loss at 1550 nm of less than0.2 dB/turn.
 9. The jumper assembly of claim 1, wherein the at least onebend performance optical fiber has an 8 mm macrobend induced loss at1550 nm of less than 0.1 dB/turn.
 10. A fiber optic assembly forperforming interconnections within a fiber optic network, the assemblycomprising: at least one microstructured optical fiber having an outersurface and comprising a core region that is surrounded by a claddingregion that comprises randomly disposed cladding material voids that arecontained within an annular region spaced from the core and outersurface respectively by a hole-free inner and outer cladding regions,the void-containing annular region having a radial width W23 in therange from 0.5 um to 20 μm; a protective covering surrounding at least aportion of the at least one microstructured optical fiber; and at leastone connector mounted upon at least one end of the at least onemicrostructured optical fiber.
 11. The fiber optic assembly of claim 10,wherein the assembly has a delta attenuation of 0.11 dB or less whenwrapped one turn about a 10 mm diameter structure at a referencewavelength of 1625 nm.
 12. The fiber optic assembly of claim 10, whereinthe assembly has a delta attenuation of 0.46 or less when wrapped oneturn about a 6 mm diameter structure at a reference wavelength of 1625nm.
 13. The fiber optic assembly of claim 10, wherein the assembly has adelta attenuation of 0.00 when wrapped 5 turns about a 6 mm diameterstructure at a reference wavelength of 1625 nm.
 14. The fiber opticjumper assembly of claim 1, wherein the core region has a radius R1 inthe range from 1 μm to 5 μm, the inner annular cladding region has aninner radius R2 in the range from 10 μm to 20 μm, and the annularhole-containing cladding region has an annular width W23 in the rangefrom 0.5 μm to 20 μm.
 15. The fiber optic assembly of claim 10, whereinthe core region has a radius R1 in the range from 1 μm to 5 μm, theinner annular cladding region has an inner radius R2 in the range from10 μm to 20 μm.